Telephone system.



E. E. KLEINSOHMIDT. TELEPHONE SYSTEM APPLIOATION FILED SEPT.8, 1910. RENEWED MAY 29, 1911.

1,062,577. Patented May 20, 1913.

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v -m U W P mum WITNESSES: IIVI/E/V T0,?

A TTOR/VEY V an EDWARD KLEKIISCHMIDT, (BF BEOGKLYN, IiiEW "EZDRK, MSIGHQE Ti) "EQUIPMENT COMPANY, A CORPORATION 63 TELEPHQNE EYSTEI'IE.

Specification of Letters Patent.

Patented May so, rare.

4, Application filed September 8, 1910, Serial No. 581,009. Renewed "May 29, 1911. Serial No. 680,121.

To all/whom it may concern:

Be it known that I, EDWARD E. KLEIN- SCHMIDT, a citizen of the United States of America, residing in the borough of Brooklyn, county .of Kings, and State of New York, have invented a certain new and useful Improvement in Telephone Systems, of which the following is a specification.

This invention relates to selective systems in which there -is a plurality of subscribers stations connecte with a central ofiice. The main circuit is composed of two conductors across which the selective source of current and the sub-station selectors are bridged. The telephonic communicating ap paratus for all stations is likewise bridged across the main conductors.

The primary purpose of this invention is to rovide a single source of current from which a plurality of telephonic apparatus at stations may receive electrical energy. In other words it is proposed to eliminate the use of local batteries. When there is but one such common telephone supply battery it would, preferably, be located at the central oifice.

The accompanying drawing is a diagram illustrating the invention.

The conductors of the main telephone circuit are marked a, b. At the central oflice, the selector source of electrical energy SB, which will hereinafter be called a battery, is in. a bridge circuit that may be traced from main conductor a through conductor 0 including a retardation coil 0, commutator brush (1, commutator plate and brush 6, through the selector battery thence through a limiting resistance BR, commutator brush f, commutator plate and brush 9, retardation coil 0 and condenser c" to main line conduct-or b. The retardation coils c, c on the side nearest the commutator are bridged by a condenser 0 The use of the condenser c and retardation coils is, as is well understood, for the purpose of preventing the bridge connection containing the battery SE from interfering with the telephonic currents. There is a ground connection on this bridge circuit from between the battery SB and balancing resistance BR, through a normallyclosed key or two point switch h, a signaling device such, for instance, as an electric lamp it, contact iece 79, contact spring it normally presse in contact with k by lever arm I, and thence to ground. The central oflice selector apparatus may be of any appropriate type or construction.

The operation, as is well understood, is as follows: When the lever arm I is moved to the right, its retracting spring returns it to normal position of rest and in such return causes it to drive a ratchet wheel that drives appropriate gears by which the commutator is operated to transmit to line reversals of current, the number of such reversals depending upon the extentof move- -ment of the lever.

Two sub-stations are shown marked respectively X and Y. At each the selector apparatus is bridged across the main conductors, the circuit be ing by wire through winding of selector magnet y" thence by wire 7' through the winding of a detent controlling magnet j and thence by wire i adjustable resistance Rhand condenser j to main line conductor 6. The selector magnet has a rocking polarized armature frame J pivoted centrally at y' and having a spring device 7' applied to it. A two arm drive pawl 70 on'the armature frame operates the selector ratchet wheel on. The armature frame also carries an insulated spring contact 12 connected by wire 01. with conductor 1' On the axis of the ratchet wheel and turning therewith is a radial contact arm 0 connected to ground through a vibrating bell VB. The reverse currents transmitted from the selector battery SB cause the rocking of armature frame J and the step-by-step actuation of the ratchet wheel, there being a sufficient number of such steps to bring the properly set radial arm 0 into contact with n. The detent controlling magnet is so wound as not to respond to the reversals of current but attracts its armature downwardly on'the first calling impulse and so retains it until after the impulses have ceased. While the armature is held down the spring controlled detent or back sto pawl p is carried into engagement with t e ratchet wheel. When contact 0 has been stepped, around into contact with n, lever arm I of the central office -selector will have returned. to normal position and carried contact h into engagement with contact 71. A circuit is thus completed from round at the sub-station through the vibrating bell VB to the axis of the ratchet wheel m thence to the main line conductor a, commutator brushes d, e, signaling battery SB, normally closed key h, signaling device it and contacts 71?, h to ground. Contact between 0 and a will occur-on the last step actuation of the ratchet wheel m by the drive pawl on the rocking armature frame at the selected station and current in the ground circuit then established will be of a polarity to hold the armature frame in such final position in which the drive pawl looks or holds the ratchet wheel. The vibrating bell VB of the selected station will now continue to ring until this circuit is broken which may be efi ec'ted by the opening of key 71. at the central office after that ofiice and the sub-station 0 erator are in telephonic communication. 6n the opening lot the ground circuit, spring j applied to the armature frame moves it away from the ratchet wheel which, being released, is returned to'zero position by the reaction of its usual spring. The interruptions of the ground signal circuit durin the operation of the vibrating signal bel are so brief that the selector magnet is not deenergized.

The telephone-outfit, bridged across the conductors a, b, for the central oflice operator is indicated by T and the circuits all being ordinary and well understood, it is unnecessary to describe them in detail. There is no local battery. A like telephone outfit T is provided for each of the substations. The common telephone battery TB is bridged across the conductors a, b, one pole thereof being connected to conductor b and the other through a resistance Rh to conductor a. If the line be of considerable length with numerous sub-stations there may be several common telephone batteries,for instance one adjacent each end of the line and the other intermediate. The condensers 0 7' j prevent short cirouiting of the telephone battery TB.

Experience has demonstrated that the disclosed system of selective calling is satis factory and efiicient and permits the employment of a common telephone battery. The invention is not, however, limited to the particular details of the calling system nor of the transmitter and selectors.

I claim:

1. A telephone system comprising two main conductors, a central station selector generator bridged across the conductors and a condenser in such bridge, selectors at a plurality of sub-stations each also bridged across the conductors and a condenser in each such bridge, a common telephone battery also bridged across the conductors and a telephone equipment at each sub-station also bridged across the conductors.

and a condenser in each telephone bridge connection.

3. A telephone system comprising two main conductors, a central calling station equipped with a calling generator,'a bridge connection for the generator, acondenser 1n said bridge connection, a telephone equipment and a permanent bridge connection across the main conductors that includes the telephone equipment; selectors at a plurality of sub-stations each bridged across the conductors, a condenser in each such bridge, substation telephone equipments bridged across the conductors and a common telephone battery also bridged across the conductors.

4. A telephone system comprising two main conductors, a central calling station equipped with a calling generator, a bridge connection including the generator, a condenser in said bridge, a telephone equipment, a permanent bridge connection across the main conductors that includes the telephone equipment and a condenser in the telephone bridge connection; selectors at a plurality of sub-stations each bridged across the conductors, a condenser in each such bridge sub-station telephone equipments bridged across the conductors, a condenser in each such bridge and a common telephone battery also bridged across the conductors.

5. A telephone system comprising two main conductors, a selector battery in a bridge circuit containing a condenser across the conductors, a plurality of selectors bridged across the conductors and respectively operated b corresponding series of current impulses rom said battery and each having a pair of normally open signal contacts brought into contact when stepped around to selected position, a ground circuit from the selected station to the central ofiice including a signal device at the selected station, said signal contacts, one of the main line conductors and the selector battery.

6. A telephone system comprising two main conductors,.a selector battery in a bridge circuit containing a condenser across the conductors, a plurality of selectors bridged across the conductors and respectively operated by corres onding series of current impulses from sai battery and each having a pair of normally open signal contacts brought into contact when stepped around to selected position, a groundcir- I cuit from the selected station to the central oifice including a signal device at the selected station, sald signal contacts, one of the main line conductors, the selector battery, a normally closed key and a signal devicevat the central oflice.

In testimony whereof, I have hereunto subscribed my name.

EDWARD E. KLEINSCHMIDT Witnesses: v

J. H. SoHUAcKENBERe,

L, L. BROWNING. 

